I read thru cover to cover and even though I am using my first 430EX II I did not hit upon a single bit of info that led to an 'ah ha' moment.
went back thru and learned nothing.
the book leads thru a desritption of what can be done, but now how and no info I didnt already get from canon's documentation.
might be just me, but take a lcose look at the content before buyingGet more detail about Canon Speedlite System Digital Field Guide.
